I don't know c very much they are two separate c programs called
1. app_talkdetect.c
and
2. app_record.c

in the app_talkdetect.c file i have to find if any voice interrupt is occurs in that file if it occurs
it will stop the process and do other things in original c programming but i have to change as instead of stopping the voice intercepted must be saved for that i have to call the app_record.c in the place of voice intercept and i have to record that voice.

Code:

code app_talkdetect.c

*//*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 1999 - 2005, Digium, Inc.
*
* Mark Spencer <markster@digium.com>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/

static char *descrip =
" BackgroundDetect(filename[|sil[|min|[max]]]): Plays back a given\n"
"filename, waiting for interruption from a given digit (the digit must\n"
"start the beginning of a valid extension, or it will be ignored).\n"
"During the playback of the file, audio is monitored in the receive\n"
"direction, and if a period of non-silence which is greater than 'min' ms\n"
"yet less than 'max' ms is followed by silence for at least 'sil' ms then\n"
"the audio playback is aborted and processing jumps to the 'talk' extension\n"
"if available. If unspecified, sil, min, and max default to 1000, 100, and\n"
"infinity respectively.\n";

/*/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 1999 - 2005, Digium, Inc.
*
* Matthew Fredrickson <creslin@digium.com>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/

static char *descrip =
" Record(filename.format|silence[|maxduration][|options])\n\n"
"Records from the channel into a given filename. If the file exists it will\n"
"be overwritten.\n"
"- 'format' is the format of the file type to be recorded (wav, gsm, etc).\n"
"- 'silence' is the number of seconds of silence to allow before returning.\n"
"- 'maxduration' is the maximum recording duration in seconds. If missing\n"
"or 0 there is no maximum.\n"
"- 'options' may contain any of the following letters:\n"
" 'a' : append to existing recording rather than replacing\n"
" 'n' : do not answer, but record anyway if line not yet answered\n"
" 'q' : quiet (do not play a beep tone)\n"
" 's' : skip recording if the line is not yet answered\n"
" 't' : use alternate '*' terminator key instead of default '#'\n"
"\n"
"If filename contains '%d', these characters will be replaced with a number\n"
"incremented by one each time the file is recorded. A channel variable\n"
"named RECORDED_FILE will also be set, which contains the final filemname.\n\n"
"Use 'show file formats' to see the available formats on your system\n\n"
"User can press '#' to terminate the recording and continue to the next priority.\n\n"
"If the user should hangup during a recording, all data will be lost and the\n"
"application will terminate. \n";

/* The next few lines of code parse out the filename and header from the input string */
if (ast_strlen_zero(data)) { /* no data implies no filename or anything is present */
ast_log(LOG_WARNING, "Record requires an argument (filename)\n");
return -1;
}

if (chan->_state != AST_STATE_UP) {
if (option_skip) {
/* At the user's option, skip if the line is not up */
LOCAL_USER_REMOVE(u);
return 0;
} else if (!option_noanswer) {
/* Otherwise answer unless we're supposed to record while on-hook */
res = ast_answer(chan);